The present application is based on Japanese Application No. 10-336607 filed on Nov. 10, 1998, herein incorporated by reference.
The present invention relates to an image synthesizing apparatus, an image synthesizing method, and a computer-readable recording medium on which an image synthesize processing program is recorded, and particularly to such an apparatus, a method, and a program which are suitable for an image containing characters.
Conventionally, a camera-type imaging apparatus has been proposed which performs imaging on a natural image, a manuscript image, or the like with splitting the image into plural regions. In such an apparatus, it is required to synthesize an image while detecting deviation among overlapping portions of the image which has been imaged with segmenting the image into plural regions.
As a method of detecting deviation of such overlapping portions of images, a sequential residual detecting method is known. In the sequential residual detecting method, images are virtually deviated from one another, and the deviation position of the highest degree of coincidence is then searched. As the degree of coincidence, the method uses the square sum of differences between pixel values, or the like. At the timing when, during the process of calculation of the degree of coincidence at a certain position, the value of the degree of coincidence is not higher than the value of the highest degree of coincidence (the minimum value of the square sums) in the previous calculations, the calculation of the degree of coincidence in this position is stopped. The calculation in the next position is then performed. As a result, wasted calculations can be reduced.
When, in addition to the vertical/lateral components, also rotation, expansion, contraction, and other components (such as distortion) are added as deviation components, however, the search space becomes so enormous that, when the sequential residual detecting method is applied as it is, the effect of reducing the complexity is not sufficiently attained.
In order to solve the above problem, the following countermeasure may be taken. The deviation position is gradually changed from a standard position to a position of a higher degree of coincidence, thereby enabling the search to reach a coincident deviation position along an efficient search path.
In this countermeasure, however, there is a tendency that, for a binary or linear image, the degree of coincidence is not smoothly changed with respect to the amount of deviation. When no further countermeasure is taken, therefore, there arises a possibility that the search is ended in the middle of a search path or at the maximal point of the degree of coincidence and the amount of deviation cannot be correctly detected.
Therefore, the technical problem which is to be solved by the invention is to provide an image synthesizing apparatus, an image synthesizing method, and a computer-readable recording medium on which an image synthesize processing program is recorded, the apparatus, the method, and the program being able to correctly detect an amount of deviation among images.